When .NET APM was installed ver (25.1.1.25). the API endpoints going to <endpoint_URL> are not processing completely.
Looking at the uploaded logs and config files, the soap message captured in the app log with DX APM .NET agent had WSCorIDSOAPHeader inserted and the apm logs showed instrumentations with WCFCorIDTracer as well.
Try skipping WCFCorIDTracer instrumentations in the app by commenting out the following line in the webservices.pbd, e.g. C:\\Program Files\\CA APM\\Introscope\\<release>\\webservices.pbd:
#TurnOn: WCFRuntimeTracing